Chapter 3 PDF

Process Design Development: Procedures 1 

Recognize potential processes Analyze the various processes  Know potential design problems  Identify data needed  

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Literature survey: Obtain data Flow sheets Equipment needed

Recognize and Apply design software Data can be found in: chemical abstract, engineering index, science citation index, Perry’s Chemical Chemic al Engineering handbook, handbook handbook of chemistry c hemistry and physics, physics, chemical processing handbook, unit operation handbook, kirk Othmer encyclopedia of chemical tech technology nology,, Ullman’s encyclopedia of industrial cchemistry hemistry.. 

Process Design Dev Development: elopment: (continues) 2

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Raw material materi al and product specification: specification: Flow Flo w rate (a priori determined from market survey)  Composition of each chemical species  Phase (gas, liquid, solid)  Temperature and pressure of the feed and the prod product uct

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Process synthesis steps: reactions, separation, phase, … 

Process Design Dev Development: elopment: (continues) 3

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Patent searc searchh Process creation: you may even improve on the existing one

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Mode of operation: batch, continuous, semi-continuous

Continuous mode of operation is always always preferred

Batch and semi-continuous processes are utilized: small production rates Intermittent production Dealing with hazardous and toxic materials

Batch vs. Continuous Continuous Factors Favoring Batch Operation 4

1. Production Rate  < 5000 ton/yr   Sometimes we select batch  < 500 ton/yr  Usually Batch  Multi-product plant 2. Market forces  Seasonal Production  Short product lifetime 

3. Operational problem  Very long reaction times  Handling slurries at very flow rate  Rapidly fouling materials

Notes 1. Continuous are typically more expensive, because of that it is only justified at high production volumes, Continuous design requires almost accurate data. However, the range of uncertainty in batch is 2.

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greater, batch greater, batc h is also more mor e flexible Such as fertilizers, we have one month of consumption, producing over a year and storing most likely will be costly. Thus operating for few month batch wise then the process can be used for another seasonal product For long reactor reactionfor time, this mean a larger a given flow we rateneed and having many multiple reactors. If the amount of slurry is small it is not feasible building a continuous plant.  Batch is more accident prone (safety) Equipment scheduling is very important issue

Process Design Dev Development: elopment: (continues) 5

Comparison between different processes is essential. Some So me processes may be eliminated easily so that there is no need to go through its design for comparison purposes. When comparing consider the followings:  

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Technical factors: flexibility flexibility,, mode of operation, special control, commercial yield, technical difficulty Raw material: present and future availability, storage, processing Waste and by product: amount value, potential markets, uses Equipment: availability, availability, material of construction, cost maintenance maintenance,, installation Plant location: area of land needed, transportation, labor availability,, climate, services, taxation availability